Comparative effectiveness of different weed management practices in onion (allium cepa l.) production

Abstract

Onion is one of the most important vegetable in Tanzania. However, yields are generally low weeds are among the major pests which reduce onion yields. A field experiment was conducted to assess the effectiveness of weed management practices in onion (Allium cepa L.) at Sokoine University of Agriculture, Horticulture unit during the dry season of October 2013 to February 2014. The experiment was laid down in a RCBD design with three replications. Three onions varieties (Red Bombay, Red Creole and Mang,ola Red) were used. Six weed management treatments using Galgan® 240 EC herbicide, Rice husks mulch, weeding once, weeding twice, weeding thrice and unweeded as control were evaluated. There were highly significant (P≤0.001) differences among varieties with respect to weed fresh weight, weed density, bulb height and weed dry weight. Onion plant height differed significantly (P≤0.01). Moreover, onion bulb yield differed significantly (P≤0.01) among varieties. It was also found that the treatments had very highly significant (P≤0.001) effect on weed fresh and dry weights, bulb diameter, bulb weight, bulb height, number of bulbs per plot and onion bulb yield. Different weed control measures also had significant differences on onion plant height (P≤0.01) and weed density (P≤0.001).Among the weed management practices, mulch was most effective, followed by Galgan® herbicide, weeding thrice, weeding twice, weeding once and last no weeding. Highest yield of onion bulbs was obtained when plots were mulched and no Onion bulb yield was recorded in control plots. Though the weeding twice and thrice treatments resulted in highest onion bulb yield, weeding is a laborious and time consuming method of weed control as compared to the use of mulch and Galgan® 240 g/l. It is therefore recommended that, the use of mulch and herbicide in onion production be promoted.